1. Field of the Invention
This invention relates generally to shim elements, and more particularly to shims of a non-displaceable, self-righting type.
2. Description of the Prior Art
Tolerances in the construction industry are such that the alignment of erected materials is never perfect. For example, the girts and subgirts of the structural framework of a building are intended to have outer faces reside in a vertically oriented working plane. Most often, the outer face of one or more of the girts or subgirts is inset from the working plane. When a panel member is erected on the framework, the fasteners are sufficiently tightened to place the panel member snug against the girt or subgirts. In the region of the out-of-plane girts or subgirts, the panel may bow inwardly creating an unsightly depression. Where the panel members have complementary mating elements along the joint edges, the mating element of the next-to-be-erected panel member cannot conform to the bowed configuration of the previously installed panel member, and cannot easily be installed.
Adjustments are required to overcome such out-of-plane deviations. The most common method of adjustment is to use shims or spacers interposed between the panel member and the out-of-plane girt or subgirt. Several types of shims or spacers have been used in the past, including rectangular pieces of material, a standard round washer with a central aperture, and a horseshoe-shaped shim.
While a shim formed of a rectangular piece of material is easily found around the jobsite, positive placement of such shims is not possible. Such shims may work loose during thermal expansion and contraction of the panels and fall off. The once-secure panel portion is now free to vibrate under varying wind conditions.
Standard round washers with a central aperture have been used and are positively placed once installed. However it is extremely difficult and very time-consuming to hold one or more of the standard round washers in position while threading the fastener through the registered central apertures.
U-shaped washers have been used and are most easily installed. The U-shaped washer is dropped over the fastener and thereafter the fastener is tightened. The U-shaped washer can work loose during thermal expansion and contraction of the panel and if rotated sufficiently about the fastener, may fall off.